Transition-joints for joining dissimilar materials

ABSTRACT

An assembly includes a first structural member made from a first material, such as aluminum, and having a first and a second flange, a second structural member having a first and a second flange and made from a second material, such as magnesium, and a third and a fourth structural member made from the first material and each having a first and second flange for contacting with the flanges of the first and second structural members so as to lock the first and second members together.

FIELD OF THE INVENTION

The present invention relates to transition-joints for joiningstructural and mechanical parts made from dissimilar materials.

BACKGROUND OF THE INVENTION

Two issues with joining dissimilar materials are material compatibilityand applicability of the joining process. More particularly, there areissues involved with joining aluminum to magnesium, to steel or tocomposites with known joining processes, such as fusion welding (e.g.,gas metal arc welding) and solid-state welding (e.g., friction stirwelding). These include metallurgical incompatibility, which results inuncontrolled cracking in welds and/or formation of brittleintermetallics; drastic differences in electromotive potential, whichmay lead to galvanic corrosion in the presence of salts and/or moisture;and incompatibility in the coefficient of thermal expansion, which couldcause formation of intense residual stresses at joints and lead tofailure under certain loading conditions, such as stress corrosion.

SUMMARY OF THE INVENTION

The invention covers a transition-joint that can be used to joindifferent materials by conventional processes that are commonly used tojoin the individual materials to themselves, but which cannot always bejoined to other materials. The new transition-joint affords moreflexibility in the design of the transitions, so the individualmaterials (e.g., steel and aluminum) can be joined welded and/or boltedthrough slip-type joints that more readily accommodate variations in thedimensional tolerances of parts, are easier to control and can result injoints with superior mechanical properties (e.g., fatigue and strength).The new transition-joints also allow the option of fabrication of thejoint away from the structures in which they will be used and the optionof fabrication of the joint as party of subassemblies later to beincorporated, through welding or bolting, into a larger structure.

In one embodiment, the present invention provides an assembly comprisinga first structural member made from a first material, said firststructural member having a flange, a second structural member made froma second material, said second structural member having a flange, athird structural member made from the first material, said thirdstructural member having at a first flange and a second flange, whereinthe flange of the first structural member contacts the first flange ofthe third structural member and the flange of the second structuralmember contacts the second flange of the third structural member, so asto lock the first member and second member together; and wherein thefirst structural member and the third structural member are joineddirectly to one another.

In another embodiment, the present invention provides an assembly,comprising a first structural member made from a first material, saidfirst structural member having a first flange and a second flange, asecond structural member made from a second material, said secondstructural member having a first flange and a second flange, a thirdstructural member made from the first material, said third structuralmember having at a first flange and a second flange, a fourth structuralmember made from the first material, said fourth structural memberhaving at a first flange and a second flange; wherein the first flangeof the first structural member contacts the first flange of the thirdstructural member, the second flange of the first structural membercontacts the first flange of the fourth structural member, the firstflange of the second structural member contacts the second flange of thethird structural member, and the second flange of the second structuralmember contacts the second flange of the fourth structural member, so asto lock the first member and second member together; and wherein thefirst structural member and the third structural member are joineddirectly to one another and the first structural member and the fourthstructural member are joined directly to one another.

The structural members of these assemblies that are made of the same orsimilar materials may be joined directly to one another by any weldingprocess known in the art, including fusion, buried arc, laser beam orgas metal buried welding. In a further embodiment, the assemblies canfurther comprise one or more adhesives joining at least two structuralmembers to one another. The assemblies can also further comprise one ormore fasteners, including bolts or rivets, joining at least twostructural members to one another.

The invention further provides methods for assembling thetransition-joints disclosed herein.

Further features and advantages of the invention will appear moreclearly on a reading of the detailed description of the embodiments ofthe invention, which is given below by way of example only withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference is madeto the following detailed description of the embodiments considered inconjunction with the accompanying drawings, in which:

FIG. 1A is one embodiment of cross-sectional view of a transition-jointassembly;

FIG. 1B is top-perspective cross-sectional view of the transition-jointassembly in FIG. 1A;

FIG. 2A is another embodiment of a cross-sectional view of atransition-joint assembly comprising a fastener;

FIG. 2B is top-perspective cross-sectional view of the transition-jointassembly in FIG. 2A;

FIG. 3 is another embodiment of a cross-sectional view of atransition-joint assembly utilizing partial-swivel type joints;

FIG. 4A is another embodiment of a cross-sectional view of atransition-joint assembly that is welded to a beam's web through aslip-fit double lap-fillet joint.

FIG. 4B is top-perspective cross-sectional view of the transition-jointassembly in FIG. 4A.

FIG. 5A is another embodiment of a cross-sectional view of atransition-joint to be intersected with a second transition-jointassembly.

FIG. 5B a lateral view of the transition-joint assembly in FIG. 5A.

FIG. 5C is top-perspective cross-sectional view of the transition-jointassembly in FIG. 5A and a second transition-joint assembly with which itis to be intersected.

FIG. 6A is another embodiment of a lateral view of intersectedtransition-joint assemblies.

FIG. 6B is top-down view of the intersected transition-joint assembliesin FIG. 6A.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to FIGS. 1A and 1B, a transition-joint assembly of oneembodiment the invention 10 includes a first structural member, in thisembodiment a top locking plate or “T” extrusion, comprising a firstmaterial (e.g., steel, magnesium, composite, etc.) 12 having flanges 18,a second structural member comprising a second material 14 havingflanges 24, and a third and a fourth structural member, in thisembodiment side locking extrusions, comprising the first material 16having flanges 20 and 22. The second structural member, in thisembodiment, has a “T” shape when viewed in cross-section. The structuralmembers 12, 14, and 16 may be made from any material suitable for atransition-joint, including aluminum, T6 temper 6061 aluminum alloy,aluminum alloy composites, steel, magnesium, organic based composites(e.g., carbon fibers bonded together) and inorganic based composites(e.g., metallic fibers braded and adhesively bonded) or similarcomposites. The flanges of the side locking extrusions 20 and 22 shouldcontact the flanges of the locking plate or “T” extrusion 18 and theflanges of the second structural member 24 sufficiently so as tomechanically interlock the structural members and prevent the firststructural member 12 and second structural member 14 from separatingonce the side locking extrusions 16 are welded to the top locking plateor “T” extrusion 12. In this embodiment, when viewed in cross-section,the third and fourth structural members 16 are adapted to conform to theouter contour of the first structural member 12 and the secondstructural member 14 when joined. The flange of the side lockingextrusions 20 forms a butt-joint with the top locking plate or “T”extrusion 28 that may be welded along its length. In a furtherembodiment, sealant or adhesive 26 can be placed between the structuralmembers 12, 14 or 16 to bond structural members to one another and/orreduce wear and corrosion of the structural members.

Referring to FIGS. 2A and 2B, the welds of a transition-joint assemblyof another embodiment of the invention 30 may be made from any weldingprocess known in the art, such as fusion-based (e.g., GMAW, GTAW, LBW,LSBW, etc.) or solid-state based (e.g., FSW, FW Plunge, etc.).Alternatively, the welds 30 need not be included, and the weldingprocess described above could be substituted with any other joining andfixation processes known in the art that ensures the mechanicalinterlocks between structural members do not separate. Thetransition-joint may include an additional component made of the firstmaterial 33 that can be welded to the first structural component 12 andan additional component made of the second material 36 welded to thesecond structural element 14. FIGS. 2A and 2B also show the use of anoptional fastener 40 in the transition-joint that can be used to preventflanges 22 of the side locking extrusions 16 from separating from thesecond structural member 14.

Another embodiment of the present invention is illustrated in FIG. 3,which shows a transition-joint utilizing a partial-swivel joint 44between the top locking plate or “T” extrusion 14 and the flanges 20 ofthe side locking extrusions 18. In this embodiment, use ofpartial-swivel type joints 44 having a radius of curvature allows theloading of the side locking extrusions 18 against the edges of the toplocking plate or “T” extrusion 46 so that they can be welded to oneanother, while allowing a firm point of contact 48 between the taperedsurface of the flanges of the second structural member and the flangesof the side locking extrusions when using a backup anvil (as duringFSW). The side locking extrusions 18 can also optionally comprise athickened lower surface 50 for improved contact with a backup anvil.

FIGS. 4A and 4B show a transition-joint assembly of the invention 10that is welded to a beam's web 60 through slip-fit double lap-filletjoints 62.

FIGS. 5A and 5B show a first transition-joint assembly of the invention80 that is to be intersected and joined with a second transition-jointassembly. FIG. 5B is a lateral view of the transition-joint assembly 80shown in FIG. 5A. A notch 82 is present in the side locking extrusions16 of assembly 80.

FIG. 5C shows the first transition-joint assembly of FIGS. 5A and 5B anda second transition-joint assembly 90 with which it is to be intersectedand joined. A notch 92 is present in the side locking extrusions 16 ofthe second transition-joint assembly 90. The notch 92 mechanically mateswith the notch 82 so that the side locking extrusions 16 of the firsttransition-joint assembly 80 contact the side locking extrusions 16 ofthe second transition joint assembly 92, the flange 18 of the firststructural member 12 of the second transition joint assembly 92 and theflange 24 of the second structural member 14 of the second transitionjoint assembly 92.

FIG. 6A shows the first and second transition-joints 80 and 90respectively of FIG. 5C fully mated with one another. Thetransition-joints 80 and 90 can be welded to each other at any contactpoints between them. The welds may be made from any welding processknown in the art, such as fusion-based (e.g., GMAW, GTAW, LBW, LSBW,etc.) or solid-state based (e.g., FSW, FW Plunge, etc.). Alternatively,the welds need not be included, and the welding process described abovecould be substituted with any other joining and fixation processes knownin the art that ensures that the intersected first and second transitionjoint assemblies 80 and 90 respectively do not separate.

FIG. 6B shows a top-down view of the first and second transition-joints80 and 90 respectively of FIG. 5C fully mated with one another. Itshould be understood that the first and second transition joints 80 and90 respectively do not need to intersect each other at a right angle asshown in FIGS. 6A and 6B.

It should be understood that the embodiments described herein are merelyexemplary and that a person skilled in the art may make many variationsand modifications without departing from the spirit and scope of theinvention. Accordingly, all such variations and modifications areintended to be included within the scope of the embodiments describedherein as defined in the appended claims.

1. An assembly, comprising: a first structural member made from a firstmaterial, the first structural member having a first flange and a secondflange; a second structural member made from a second material, thesecond structural member having a first flange and a second flange; athird structural member made from the first material, the thirdstructural member having a first flange and a second flange; a fourthstructural member made from the first material, the fourth structuralmember having a first flange and a second flange; wherein the firstflange of the first structural member contacts the first flange of thethird structural member, the second flange of the first structuralmember contacts the first flange of the fourth structural member, thefirst flange of the second structural member contacts the second flangeof the third structural member, and the second flange of the secondstructural member contacts the second flange of the fourth structuralmember; and wherein the first structural member and the third structuralmember are joined directly to one another at a point of contact betweenthe first structural member and the first flange of the third structuralmember, and the first structural member and the fourth structural memberare joined directly to one another at a point of contact between thefirst structural member and the first flange of the fourth structuralmember, so as to lock the first structural member and second structuralmember together.
 2. The assembly of claim 1, wherein the firststructural member and the third structural member are joined directly toone another by welding at a point of contact between the firststructural member and the first flange of the third structural memberand the first structural member and the fourth structural member arejoined directly to one another by welding at a point of contact betweenthe first structural member and the first flange of the fourthstructural member.
 3. The assembly of claim 1, wherein the firststructural member is a top locking plate or “T” extrusion.
 4. Theassembly of claim 1, wherein the second structural member has a “T”shape when viewed on cross-section.
 5. The assembly of claim 2, whereinthe point of contact between the first structural member and thirdstructural member comprises a partial swivel type joint.
 6. The assemblyof claim 1 wherein the first and second structural members contact eachother.
 7. The assembly of claim 6, wherein the third and fourthstructural members substantially conform to the outer contour of thefirst structural member and second structural member when the assemblyis viewed on cross-section.
 8. The assembly of claim 1, furthercomprising one or more sealants or adhesives joining at least twostructural members to one another.
 9. The assembly of claim 1, furthercomprising one or more fasteners joining at least two structural membersto one another.
 10. The assembly of claim 9, wherein the one or morefasteners comprise bolts or rivets.
 11. A method comprising the stepsof: providing a first structural member made from a first material, saidfirst structural member having a first flange and a second flange;providing a second structural member made from a second material, saidsecond structural member having a first flange and a second flange;providing a third structural member made from the first material, saidthird structural member having at a first flange and a second flange;providing a fourth structural member made from the first material, saidfourth structural member having at a first flange and a second flange;contacting the first flange of the first structural member with thefirst flange of the third structural member, the second flange of thefirst structural member with the first flange of the fourth structuralmember, the first flange of the second structural member with the secondflange of the third structural member, and the second flange of thesecond structural member with the second flange of the fourth structuralmember; and directly joining the first structural member and the thirdstructural member to one another at a point of contact between the firststructural member and the first flange of the third structural member;and directly joining the first structural member and the fourthstructural member to one another at a point of contact between the firststructural member and the first flange of the fourth structural member,thereby locking the first structural member and second structural membertogether.